Circuit arrangement



Aug. 15, 1933. J. A. WILLOUGHBY 1,922,650

CIRCUIT ARRANGEMENT Filed D90. 18, 1928 gwumtoz Patented Aug; 15; 1933' PATENT: OFFICE 7 1,922,850 CIRCUIT ARRANGEMENT John A. Willoughby, Cambridge, Mass.

Application December 1a, 1928 Serial No. 326,879

3 Claims. (01. zsc-sei My invention relates to circuit arrangements in general and more specifically to thermionic tube circuit arrangements for producing high frequency electrical energy.

' An object of my invention is to provide a circuit arrangement utilizing a thermionic tube havingmore than three electrodes whereby the additional electrodes are employed to further amplify the generated energy.

Another object of my invention is to provide a circuit arrangement wherein a mechanically vibratile element is employed in combination with a thermionic tube having four or more electrodes and whereby the mechanically vibratile element is protected from an overload condition.

Still another object of my invention is to provide a circuit arrangement for generatingJoscillations of electrical energy of uniform frequency and of greater amplitude than has heretofore been possible.

Other and further objects of my invention are to provide certain improvements in the circuit arrangements employing thermionic tubes having more than three electrodes whereby the additional electrodes serve to increase the efliciency of the system.

A better understanding of the oscillator system of my invention can be had by referring to the specification following and to the accompanying drawing which. is a schematic circuit diagram showing the embodiments of my invention.

In 'piezo electric crystal controlled oscillator systems the generated signaling energy is of substantially constant frequency. This constant frequency may be likewise obtained by using mechanically vibratile elements other than quartz crystals having piezo electric properties. For the purpose of illustration throughout the following specification, the piezo electric element or crystal will be referred to as mechanically vibratile element. The oscillator system of my invention employs a thermionic tube of the type having more than three electrodes. Such a thermionic tube is illustrated in the accompanying drawing. Referring to the thermionic tube and associated circuits in detail the operation and advantages will be clearly understood. Thermionic tube 1 is of the type having a cathode 2, control electrode 3, anode 4 and auxiliary electrode 5. Cathode 2 is heated to incandescence and caused to liberate electrons. The energy for causing such liberation of electrons may be derived from an alternating current stant frequency control device.

transformer 6. Oscillations of electrical energy source associated with the, primary winding of transformer 6. The secondary terminals of transformer 6 are. connected to the two cathode terminals. Anode 4 is supplied with a potential of positive polarity in respect to cathode 2. This potential is derived from source 7. Control electrode 3 of thermionic tube 1 is supplied with a potential from source 8. This potential is of the proper value and polarity in respect to cathode 2 to obtain the desired operational characteristics. The characteristiccurve of the tube may be altered by this source of ener in the manner desired for best results. As shown in the drawing, source 8 may conveniently be connected to apply to control grid 3 a potential negative with respect to cathode 2, which will be suitable for operation in many cases.

Mechanically vibratile element 9 is connected in the input circuit of thermionic tube 1, the connections leading to cathode 2 and control electrode 3. Element 9 has natural frequency characteristics corresponding approximately to the fundamental frequency to be generated or a multiple frequency thereof and is therefore a con- Anode 4 is con- 30 nected to inductance 11 by means of capacity 10: Capacity 12 is connected in parallel with inductance 11 through ammeter l3. Auxiliary electrode 5 is electrically connected to adjustable contact member 14, the latter of which is associated with inductance 11. Capacity 10a is connected in series with theconnection between cathode 2 and inductance 11. High frequency choke coils 15, 16, 19 and 20 are adapted to exclude high frequency energy from sources 8, 7 and transformer 6. Capacities 21 and 22 are connected in series, the center tap of the connection connected to sources 7 and 8 and to the electrical center 18 of the secondary of transformer 6.

The operation of the oscillator system of my invention is as follows: Sources 7 and 8 are caused to energize electrodes 4 and 3 respectively subsequent to the energization of cathode 2 by take place in the output circuit, which oscillations are sustained by element '9 in the input circuit. Contact member 14 is associated with inductance 11 at, a position in respect to the electrical distribution of high frequency energy whereby a potential difference exists between electrode 5 and cathode 2. The phase relation of electrodes 3 and 5 is maintained the same. Both of these electrodes are positive at the same instant and negative at the next instant. The position of adjustable contact 14 on plate coil 11 with respect to the contact 24, which is maintained at ground potential, determines the potential of auxiliary grid 5. Contact 14 is adjusted so that the potential of auxiliary grid is maintained in phase with the potential of grid 3, and the potentials of the two grids have the same sense at a given instant but may have different magnitudes. The energy in the output circuit therefore controls the electron stream from'cathode 2 to anode 4 and produces the same result as if the output energy were fed back through a circuit to inner grid 3 and the effect upon the output caused by the input energy applied from the input circuit including the piezoelectric crystal to the inner grid 3, is greatly increased, without overloading the piezo electric crystal. This is in efiect, to provide a feed back of the energy from the output circuit to the input circuit. This method for causing such transfer of energy or feed back aflords greater eiiiciency and increases the energy output of the oscillator.

modifications are possible including the use of two or more of such multi-electrode thermionic tubes connected in an electrically balanced circuit arrangement. Connections are established with the inductance included in the anode output circuit and the auxiliary electrodes whereby a potential difference of the generated energy exists. This method provides a balanced circuit arrangement wherein the proper phase relation exists at all times and whereby high frequency energy of greater value may be generated. The increased energy in the output circuit does not depend upon the ability of the crystal or other mechanically vibratile element to adequately withstand such increased energy. Therefore the generated energy will be of a constant frequency and substantially uniform irrespective of the power generated. It is obvious that oneadvantage of the oscillator system of my invention lies in the fact that the crystal or other mechanically vibratile element employed to maintain the frequency constant, is not subjected to an overload notwithstanding the increased amount of power generated. This feature afiords an oscillator system well suited to be employed for generation of harmonic frequencies having anamplitude of appreciable value for further amplification.

The circuit arrangements of my invention may be employed to receive high frequency signaling energy wherein the incoming signaling energy is rectified and amplified. The incoming signaling energy may be coupled to the output circuit associated with the auxiliary electrodes constituting means for obtaining regeneration.

Other modifications of the circuit arrangement of my invention are possible. Mechanically vibratile'element 9 may be replaced by an input circuit of such a circuit as shown herein will afford an amplifier having great possibilities. While I have shown a piezo electric crystal element in the circuit arrangement of my invention, I desire that it be understood that this element may be replaced by a mechanical oscillator composed of metal or alloys such as nickel and other metals which when influenced by alternating current will exhibit magneto strictive properties which in turn will hold the frequency constant. 1

Many modifications of my invention are possible and I desire that it be understood that my invention is not to be restricted to the foregoing specification or the accompanying drawing, and that no limitations upon my invention are intended except such as are imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. An oscillator comprising a thermionic tube having a cathode, an anode, acontrol grid and an auxiliary grid, an input circuit connected between said control grid and said cathode, an electromechanical vibrator connected in said input circuit, means for negatively biasing said control grid with respect tosaid cathode, an output circuit connected between said anode and cathode, and a feed-back connection between said output circuit and said auxiliary grid.

2. In an oscillator generating system, an electron tube having a cathode, a control grid, an auxiliary grid and an anode, a constant frequency control device connected between said control grid and said cathode, means for negatively biasing said control grid with respect to said cathode, and an output circuit comprising an inductance coil having variable taps, one of said taps being connected to said anode, another of said taps being connected by a feed-back circuit to said auxiliary grid, and a third one of said taps being connected to said cathode for completing the output circuit thereto.

3. In an electron tube oscillator system, an electron tube having a cathode, control grid, auxiliary grid and an anode, an output inductance coil having variable taps, an input circuit connected between said control grid and said cathode, a constant frequency control device connected in said input circuit, a connection to a variable tap on said output inductance to said anode, an independent connection from another variable tap on said output inductance to said cathode and another independent tap on said output inductance to said auxiliary grid.

JOHN A. WILLOUGHBY. 

